1. Field of the Invention
The present invention relates to a soft magnetic film comprising Fe and magnetic elements other than Fe that are used as a core material of a recording thin film magnetic head (an inductive head) integrated, for example, into a hard disk device. In particular, the present invention relates to a soft magnetic film capable of improving a saturation magnetic flux density Bs and decreasing a coercive force Hc and a thin film magnetic head using the soft magnetic film, and a process for manufacturing the soft magnetic film and a process for manufacturing the thin film magnetic head.
2. Description of the Related Art
A NiFe based alloy (a permalloy) has been generally used for a core material constituting a recording thin film magnetic head (an inductive head) integrated, for example, into a hard disk device.
The NiFe based alloy has relatively excellent soft magnetic characteristics that render the alloy one of the most frequently used magnetic materials due to its easiness for forming a plating layer.
The conventional NiFe based alloy comprises about 55% by mass of Fe with a saturation magnetic flux density Bs of about 1.5 T.
However, it has been required for further improvement of the recording density to enhance the saturation magnetic flux density Bs of the NiFe alloy.
Since the saturation magnetic flux density Bs mainly depends on the chemical composition of Fe, it has been emphasized to increase the chemical composition of Fe in the NiFe based alloy in order to enhance the saturation magnetic flux density Bs.
The conventional core material made of, for example, the NiFe based alloy has been formed with a uniform composition throughout the alloy, because the saturation magnetic flux density Bs has been considered to be stabilized by making the alloy to have a uniform composition.
Therefore, it has been conjectured that a higher saturation magnetic flux density Bs might be obtained by attempting to increase the chemical composition of Fe while maintaining a uniform composition of the core material.
However, it was found that the coercive force Hc is rather increased by increasing the chemical composition of Fe, although the saturation magnetic flux density is certainly increased. One reason of this phenomenon may be attributed to coarsened crystal grains as a result of increasing the chemical composition of Fe while maintaining a uniform composition.
An increased coercive force is not preferable since magnetization inversion of the core material becomes dull to deteriorate recording characteristics of the magnetic head.